LT1585A/LT1585A-3.3 WWSI PLIFIED SCHE ATIC VIN + – THERMAL LIMIT VOUT ADJ GND LT1585A • BD FOR FIXED VOLTAGE DEVICE UUWUAPPLICATIONS INFORMATIONGeneral The LT1585A/LT1585A-3.3 3-terminal regulators are Current generation microprocessors cycle load current easy to use and have all the protection features expected from almost zero to amps in tens of nanoseconds. Output in high performance linear regulators. The devices are voltage tolerances are tighter and include transient re- short-circuit protected, safe-area protected and provide sponse as part of the specification. The LT1585A/ thermal shutdown to turn off the regulators should the LT1585A-3.3 are specifically designed to meet the fast junction temperature exceed about 150°C. The regulators current load-step requirements of these microprocessors include an adjustable and a fixed 3.3V version. and save total cost by needing less output capacitance in order to maintain regulation. These ICs are pin compatible with the LT1083/LT1084/ LT1085 family of linear regulators but offer lower dropout Stability voltage and faster transient response. The trade-off for this improved performance is a 7V maximum supply voltage. The circuit design in the LT1585A/LT1585A-3.3 requires Similar to the LT1083/LT1084/LT1085 family, the the use of an output capacitor as part of the frequency LT1585A/LT1585A-3.3 regulators require an output ca- compensation. For all operating conditions, the addition pacitor for stability. However, the improved frequency of a 100µF solid tantalum or aluminum electrolytic on the compensation permits the use of capacitors with much output ensures stability. Normally, the LT1585A/ lower ESR while still maintaining stability. This is critical in LT1585A-3.3 can use smaller value capacitors. Many addressing the needs of modern, low voltage, high speed different types of capacitors are available and have widely microprocessors. varying characteristics. These capacitors differ in capaci- 1585afa 5